Page 10 - MetalForming May 2009

TechUpdate
Sheetmetal Fabricator Delivers Custom-Outfitted Trailer for U.S. National Guard
The U.S. National Guard
recently contracted SRI Inter-
national, a nonprofit research
institute in Menlo Park, CA, to
design and produce a bat- tery-service trailer (BST) capa-
ble of simultaneously charging
2048 lithium-ion batteries.
The batteries are used to
power portable instrumentation
during National Guard field-
training exercises. SRI then
provided an empty 48-ft. refrigerated trailer to sheet-
metal fabricator Airtronics
Metal Products, in San Jose,
CA, for modification and outfitting to house the batteries.
The BST called for Airtronics to design, fabricate and install 16 special 19-in. equipment racks to house the charging units; fan-tray and fire-sup- pression systems; and HVAC and duct sys- tems. Airtronics also designed and
installed AC prime power distribution wiring, and fabricated and installed four weather-worthy cable containment boxes beneath the trailer, each box holding a 250-lb. power cable.
Building the cabinets and racks came easy, as this is Airtronics’ core compe- tency. The real challenges were design-
ing and planning the electrical systems to allow powering the trail- er from four separate external gen- erators supplying a total of 150 kW, and balancing the airflow through each rack. The project required sophisticated problem solving to develop a bulk charging environ- ment with special cooling and venting requirements, and emer- gency back-up electrical, lighting and power-distribution systems.
Because uniform air flow and cooling around the chargers is essential to reliable operation, Airtronics built special air plenums
and HVAC cooling ducts to maintain an equipment temperature of 35 C. It also developed and installed standard and emergency lighting systems along with all associated circuitry for the chargers, HVAC and system controls.
Airtronics: 408/977-7800; www.airtronics.com
Hydraulic-Press Duo Assemble Safety-Critical Ball Joints
ZF Commercial Suspension Systems & Components, LLC, Lancaster, SC, a Tier One supplier of chassis components for Class 8 trucks, recreational vehicles and military vehicles, recently took on pro- duction of inline ball-joint assemblies.
Until 2008, the assemblies had been imported from a ZF facility in Europe to service the North American market.
To take on the task, ZF installed a ball-joint assembly cell consisting of two hydraulic presses, from Multipress,
Columbus, OH, that meet extremely tight specifications for ram-position con- trol: ±0.0015 in. Multipress sup- plied custom-con- figured 100- and 50-ton floor- mounted C-frame presses, each fea- turing electronic and mechanical subsystems to ensure the speci- fied accuracy on
a consistent basis. A Delta motion con- troller works in concert with an Allen- Bradley PLC to divide the speed of the downward ram stroke into three stages, with maximum deceleration occurring within 0.10 in. of contact with the part. The combined action of an electronic timer and a pressure transducer deter- mine dwell time and ram reversal, to ensure that time and pressure on the workpiece fall within preprogrammed lim- its. A linear transducer built into the hydraulic cylinder controls the ram con- tact position within the ±0.0015-in. specified tolerance.
Multipress, which installed the press- es in July 2008, provided other fea- tures: a touchscreen operator interface, storage of multiple recipes for various ball joint sizes and shapes, and light curtains and hard guarding for operator safety. Multipress, Inc.: 614/228-0185; www.multipress.com
8 METALFORMING / MAY 2009
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